1. Technical Field of the Invention
The present invention generally relates to packet-switched networks. More particularly, and not by way of any limitation, the present invention is directed to method and apparatus for scalable selective backpressure and traffic monitoring and shaping in such networks.
2. Description of Related Art
Currently in Ethernet switches, there exists no scalable mechanism for identifying the ingress port of a switch, such as a switched Ethernet MAN, for example, from which a packet or frame arrives at a given egress port. On the contrary, the only manner in which the ingress port can be identified is by determining the source media access control (“MAC”) address of the ingress port; however, determining this address is complex and time-consuming, requiring the performance of a significant number of data look-ups. Moreover, this scheme is not scalable.
There are many situations in which knowledge of the identity of the ingress port at which a packet originated would be useful. For example, the information could be used to identify aggressive traffic aggregates, thereby facilitating the provision of fairness per input port. The information could also be used in implementing schemes for improving fairness within intra-aggregates at egress ports; accordingly, enhancements such as selective backpressure can be incorporated within the switch, in contrast to current IEEE 802.3x. The information could be used to facilitate selective egress shaping and facilitates the collection of input/output port traffic distribution statistics.
Preferably, a mechanism used to determine the ingress port of each packet that arrives at a given egress port would be implemented such that there would be no need for standardization; that is, the mechanism would be confined to a given switch. Moreover, such a mechanism should be scalable and applicable to multicast traffic.